Thailand's army-backed government says it will seize 21 bank accounts with assets worth 52.9 billion baht (US$1.53 billion) from ousted Prime Minister Thaksin Shinawatra and his wife.
The announcement from the Asset Examination Committee (AEC), established after a September coup against Thaksin, followed months of investigations into alleged corruption during his five years in office.
No charges have been filed in court, but the AEC said in a statement it had come to the conclusion that "Thaksin and his cronies had been corrupt and committed wrongdoings".
AEC committee member Kaewsun Atibhodhi told a news conference the seizure order was not final and said Thaksin, who has not been allowed to return to Thailand since the coup, could challenge it in court.
"We have to confiscate these assets for now. The AEC has enough evidence to believe that he has committed wrongdoings," Kaewsun said.
A former policeman and telecoms tycoon, Thaksin came to power in 2001 as head of the Thai Rak Thai (Thais Love Thais) party, promising to improve the lives of the rural poor with universal public health care and cheap credit schemes.
He was wildly popular in the countryside, but critics and political opponents said he used his vast wealth to blind voters to "policy corruption" under which companies such as his family's Shin Corp telecoms empire benefited unfairly.
The $3.8 billion sale of Shin Corp to Singapore state investment company Temasek, which netted Thaksin's family $1.9 billion, in early 2006 triggered the mass street protests that led ultimately to the army's decision to launch Thailand's 18th coup in 75 years of on-off democracy.
"They have illegally obtained wealth through abuses of power to benefit Shin Corp," the AEC statement said.
Thaksin, who was in New York at the time of the coup, has spent most of his time since then either in London or travelling round Asia playing golf and giving interviews that have upset Bangkok's military rulers.
His Bangkok-based lawyer, Noppadol Pattama, vowed to fight the ruling, which he described as "an affront to the rule of law that tarnishes Thailand's image in the international arena".
"It is a political decision that is legally baseless. The aim is to prevent the ex-PM and his wife from running their own normal lives," he told Reuters. Sak Kohsaengruang, another AEC committee member, said Thaksin had 60 days in which to appeal but would have to prove where his cash came from if he wanted to see it again.
The AEC highlighted five areas in which it said it had most evidence of graft against Thaksin: his wife's purchase of a prime plot of Bangkok real estate, a national rubber saplings project, the purchase of high-tech bomb scanners for Bangkok's new airport, a national lottery and loans from a state-run bank.